Non-specific Irreversible platelet cyclooxygenase inhibitor
(COX-1 and 2) via acetylation of serine residues → ↓formation PG precursors.
- Inhibits formation of thromboxane (TXA) → inhibit aggregation
- At higher doses prostacyclin (PFI2) synthesis also inhibited → vasoconstriction (but endothelium can regenerate COX)

Allosteric, reversible antagonist at P2Y12-R (an ADP receptor), preventing activation of glycoprotein IIb/IIIa→ prevents platelet crosslinking

- PO. BA. 50%.
- 300mg Loading. 100mg maint.

BA=40%

85% protein binding, pKa 3

Vd 10L

- Converted to salicylic acid in GI mucosa and liver
- Hepatic conjugation (saturable)

Metabolized by CYP3A4

- Renal as salicylate

- T1/2b 15~20 mins when first order
- Dur: 4-6 hrs. (Effect on platelet aggregation will last life of current cohort of platelets (7-10 days)

Bleeding
Bronchospasm, Renal toxicity
Reye’s Syndrome, GI ulceration
Caution with other anticoagulants

Antiplatelet

Antiplatelet

COX inhibitor

ADP Receptor Antagonist - Thienopyridine

Level 1

Level 3

Platelet inhibition

Platelet inhibition